Bioenergy crops, which are utilized for biofuel production, could potentially have a significant impact on climate change according to recent studies. These investigations have found that the conversion of annual plants to perennial bioenergy crops might result in a cooling effect in the regions they’re grown. The study involved several scenarios for future bioenergy crop cultivation, simulating their potential impacts on the climate.
Understanding Bioenergy Crops and Biofuels
Crops that are used to produce or manufacture biofuels are referred to as biofuel or bioenergy crops. This is often paralleled with the term “energy crops”. Prominent examples of these plants include wheat, corn, main edible oilseeds/edible oils, sugarcane, among others.
Biofuels possess several advantages over traditional fossil fuels, such as cleaner burning capacity, lesser emission of pollutants, and greenhouse gases like carbon dioxide. They’re widely recognised as environmentally friendly energy options, and are often blended with petrol by energy companies.
Study Methodology and Bioenergy Crop Samples
The researchers selected bioenergy crops including eucalyptus, poplar, willow, miscanthus, and switchgrass for the study. Special attention was placed on studying the choice of crop type, the original land use type where bioenergy crops were expanded, the total cultivated area, and its spatial distribution patterns.
Impacts of Bioenergy Crop Cultivation
Although the cultivation of bioenergy crops covers only about 3.8% ± 0.5% of the global total land area, they exert powerful regional biophysical effects. This leads to a net change in global air temperature of between −0.08 ~ +0.05 degrees Celsius. It is projected that after 50 years of extensive bioenergy crop cultivation, the global air temperature would decline by 0.03~0.08 °C.
Effects on Carbon Capture and Storage
Wide-scale bioenergy crop cultivation combined with carbon capture and storage (BECCS) is considered a crucial negative emission technology (NET). This combination is significant in extracting CO2 from the atmosphere.
Spatial Variation in Temperature Change
Large-scale bioenergy crop cultivation globally results in a biophysical cooling effect. However, temperature changes vary significantly across regions and have substantial inter-annual variability. Additionally, these changes can establish critical climate teleconnections to other parts of the world.
Preserving Permafrost
Among the noted effects, an intense cooling effect has been identified in Eurasia, specifically between 60°N and 80°N. This could result in shielding permafrost from thawing or reducing methane emissions from wetlands. Permafrost is defined as any ground that stays completely frozen—32°F (0°C) or colder—for at least two years.
Comparative Performance of Eucalypt and Switchgrass
Cultivating eucalyptus has generally shown to have stronger cooling effects than switchgrass, suggesting its superiority in terms of biophysical land cooling. Notably, replacing forests with switchgrass could result in biophysical warming effects and may release more carbon via deforestation than converting other short vegetation to bioenergy crops.